Catheter with ablation needle and mapping assembly

ABSTRACT

The invention is directed to a catheter that creates enhanced lesions using a needle electrode and can simultaneously map electrical activity at a plurality of points using an enhanced mapping assembly. The catheter comprises an elongated catheter body having at least one lumen extending longitudinally therethrough. A needle control handle is provided at the proximal end of the catheter body. A needle electrode assembly extends through the catheter body and needle control handle and has a proximal end attached to the needle control handle and a distal end within the distal end of the catheter body. A mapping assembly is mounted at the distal end of the catheter body and comprises at least two flexible spines. Each spine has a proximal end attached at the distal end of the catheter body and a free distal end. Each spine carries at least one electrode. The distal end of the needle electrode assembly is extendable past the proximal end of the mapping assembly upon manipulation of the needle control handle.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.10/693,553, entitled CATHETER WITH ABLATION NEEDLE AND MAPPING ASSEMBLY,filed Oct. 24, 2003, the entire contents of which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

Radiofrequency (RF) ablation of cardiac and other tissue is a well knownmethod for creating thermal injury lesions at the tip of an electrode.Radiofrequency current is delivered between a skin (ground) patch andthe electrode. Electrical resistance at the electrode-tissue interfaceresults in direct resistive heating of a small area, the size of whichdepends upon the size of the electrode, electrode tissue contact, andcurrent (density). See Avitall B, Helms R. Determinants orRadiofrequency-Induced Lesion Size in Huang S K S, Wilber D J (eds.):Radiofrequency Catheter Ablation of Cardiac Arrhythmias: Basic Conceptsand Clinical Applications, b 2 ^(nd) ed. Armonk, N.Y., Futura PublishingCompany, Inc., 2000: 47-80. Further tissue heating results fromconduction of heat within the tissue to a larger zone. Tissue heatedbeyond a threshold of approximately 50-55° C. is irreversibly injured(ablated). See Nath S, and Haines D E. Pathophysiology of LesionFormation by Radiofrequency Catheter Ablation, in Huang S K S, Wilber DJ (eds.): Radiofrequency Catheter Ablation of Cardiac Arrhythmias: BasicConcepts and Clinical Applications, 2^(nd) ed. Armonk, N.Y., FuturaPublishing Company, Inc., 2000: 26-28.

Resistive heating is caused by energy absorption due to electricalresistance. Energy absorption is related to the square of currentdensity and inversely with tissue conductivity. Current density varieswith conductivity and voltage and inversely with the square of radiusfrom the ablating electrode. Therefore, energy absorption varies withconductivity, the square of applied voltage, and inversely with thefourth power of radius from the electrode. Resistive heating, therefore,is most heavily influenced by radius, and penetrates a very smalldistance from the ablating electrode. The rest of the lesion is createdby thermal conduction from the area of resistive heating. See Lin J,Physical Aspects of Radiofrequency Ablation, in Huang S K S, Wilber D J(eds.): Radiofrequency Catheter Ablation of Cardiac Arrhythmias: BasicConcepts and Clinical Applications, 2^(nd) ed. Armonk, N.Y., FuturaPublishing Company, Inc., 2000: 14-17. This imposes a limit on the sizeof ablation lesions that can be delivered from a surface electrode.

Theoretical methods to increase lesion size would include increasingelectrode diameter, increasing the area of electrode contact withtissue, increasing tissue conductivity and penetrating the tissue toachieve greater depth and increase the area of contact, and deliveringRF until maximal lesion size has been achieved (60-90 seconds for fullmaturation).

The electrode can be introduced to the tissue of interest directly (forsuperficial/skin structures), surgically, endoscopically,laparoscopically or using percutaneous transvascular (catheter-based)access. Catheter ablation is a well-described and commonly performedmethod by which many cardiac arrhythmias are treated. See Miller J M,Zipes D P. Management of the Patient with Cardiac Arrhythmias. InBraunwald E, Zipes D, Libby P (eds): Heart Disease: A Textbook ofCardiovascular Medicine, 6^(th) Ed. Philadelphia, Pa., W.B. SaundersCompany, 2001: p742-752. Needle electrodes have been described forpercutaneous or endoscopic ablation of solid-organ tumours, lungtumours, and abnormal neurologic structures. See, for example, McGahan JP, Schneider P, Brock J M, Tesluk H. Treatment of Liver Tumors byPercutaneous Radiofrequency Electrocautery. Seminars in InterventionalRadiology 1993; 10: 143-149; Rossi S, Fomari F, Buscarini L.Percutaneous Ultrasound-Guided Radiofrequency Electrocautery for theTreatment of Small Hepatocellular Carcinoma. J Intervent Radiol 1993; 8:97-103; and Livraghi T, Goldberg S N, Lazzaroni S, Meloni F, Monti F,Solbiati L. Saline-enhanced RF tissue ablation in the treatment of liverMetastases. Radiology 1995; 197(P): 140 (abstr)].

Catheter ablation is sometimes limited by insufficient lesion size. Seede Bakker J M T, van Capelle F J L, Janse M J et al. Macroreentry in theinfarcted human heart: mechanism of ventricular tacycardias with a“focal” activation pattern. J Am Coll Cardiol 1991; 18:1005-1014;Kaltenbrunner W, Cardinal R, Dubuc M et al. Epicardial and endocardialmapping of ventricular tachycardia in patients with myocardialinfarction. Is the origin of the tachycardia always subendocardiallylocalized? Circulation 1991; 84: 1058-1071. Stevenson W G, Friedman P L,Sager P T et al. Exploring postinfarction reentrant ventriculartachycardia with entrainment mapping. J Am coll Cardiol 1997; 29:1180-1189. Ablation of tissue from an endovascular approach results notonly in heating of tissue, but of heating of the electrode. When theelectrode reaches critical temperatures, denaturation of blood proteinscauses coagulum formation. Impedance can then rise and limit currentdelivery. Within tissue, overheating can cause evaporation of tissue orblood water and steam bubble formation (steam “pops”) with risk ofuncontrolled tissue destruction or undesirable perforation of bodilystructures. In cardiac ablation, clinical success is sometimes hamperedby inadequate lesion depth and transverse diameter even when usingcatheters with active cooling of the tip. See Soejima K, Delacretaz E,Suzuki M et al. Saline-cooled versus standard radiofrequency catheterablation for infarct-related ventricular tachycardias. Circulation 2001;103:1858-1862. Theoretical solutions have included increasing theelectrode size (increasing contact surface and increasing convectivecooling by blood flow), improving electrode-tissue contact, activelycooling the electrode with fluid infusion, changing the materialcomposition of the electrode to improve current delivery to tissue, andpulsing current delivery to allow intermittent cooling.

Needle electrodes improve contact with tissue and allow deep penetrationof current delivery to areas of interest. Ablation may still be hamperedby the small surface area of the needle electrode such that heatingoccurs at low power, and small lesions are created.

Additionally, it is desirable to map the electrical activity in theheart before, during or after ablation. If the mapping can be performedwith the same catheter used for ablation, the user avoids the need forcatheter exchange. Moreover, it is desirable to include a mappingassembly on the catheter comprising a plurality of electrodes that canbe used to simultaneously map electrical activity at different positionswithin the heart to provide more efficient mapping.

SUMMARY OF THE INVENTION

The present invention addresses the above concerns by providing acatheter that creates enhanced lesions using a needle electrode and cansimultaneously map electrical activity at a plurality of points using anenhanced mapping assembly. The catheter comprises an elongated catheterbody having at least one lumen extending longitudinally therethrough. Aneedle control handle is provided at the proximal end of the catheterbody. A needle electrode assembly extends through the catheter body andneedle control handle and has a proximal end attached to the needlecontrol handle and a distal end within the distal end of the catheterbody. A mapping assembly is mounted at the distal end of the catheterbody and comprises at least two flexible spines. Each spine has aproximal end attached at the distal end of the catheter body and a freedistal end. Each spine carries at least one electrode. The distal end ofthe needle electrode assembly is extendable past the proximal end of themapping assembly upon manipulation of the needle control handle.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a side plan view of an embodiment of a catheter of the presentinvention.

FIG. 2 is a side cross-sectional view of the needle control handle wherethe needle electrode assembly is in a retracted position.

FIG. 3 is a schematic side cross-sectional view of the distal end of thedistal shaft, including the proximal end of the mapping assembly.

FIG. 4 is a side cross-sectional view of the thermocouple mounted in theneedle electrode assembly.

FIG. 5 is a side cross-sectional view of the catheter body, includingthe junction between the proximal shaft and the distal shaft.

FIG. 6 is an end cross-sectional view of the distal shaft of thecatheter body shown in FIG. 5 along line 6-6.

FIG. 7 is an end cross-sectional view of the proximal shaft of thecatheter body shown in FIG. 5 along line 7-7.

FIG. 8 is a side view of a mapping assembly according to the invention.

FIG. 9 is a perspective view of a support structure according to thepresent invention.

FIG. 10 is a side cross sectional view of a portion of the catheter tipsection showing one means for attaching the puller wire.

FIG. 11 is a top cross sectional views of a preferred puller wireanchor.

FIG. 12 is a side cross sectional views of the puller wire anchor ofFIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, the catheter 10 comprises an elongated catheter body12 having a proximal shaft 13 and a distal shaft 14, a mapping assembly15 mounted at the distal end of the distal shaft, a deflection controlhandle 16 attached to the proximal end of the proximal shaft, and aneedle control handle 17 attached indirectly to the catheter bodyproximal to the deflection control handle.

With reference to FIGS. 5 and 7, the proximal shaft 13 comprises asingle, central or axial lumen 18. The proximal shaft 13 is flexible,i.e., bendable, but substantially non-compressible along its length. Theproximal shaft 13 may be of any suitable construction and made of anysuitable material. A presently preferred construction comprises an outerwall 22 made of polyurethane or nylon. The outer wall 22 comprises animbedded braided mesh of stainless steel or the like to increasetorsional stiffness of the proximal shaft 13 so that, when thedeflection control handle 16 is rotated, the distal shaft 14 of thecatheter 10 will rotate in a corresponding manner.

The outer diameter of the proximal shaft 13 is not critical, but ispreferably no more than about 8 French. Likewise the thickness of theouter wall 22 is not critical. In the depicted embodiment, the innersurface of the outer wall 22 is lined with a stiffening tube 20, whichcan be made of any suitable material, preferably polyimide. Thestiffening tube 20, along with the braided outer wall 22, providesimproved torsional stability while at the same time minimizing the wallthickness of the catheter, thus maximizing the diameter of the singlelumen. The outer diameter of the stiffening tube 20 is about the same asor slightly smaller than the inner diameter of the outer wall 22.

As shown in FIGS. 5 and 6, the distal shaft 14 comprises a short sectionof tubing 19 having three lumens, namely an infusion lumen 30, a pullerwire lumen 32 and a lead wire lumen 34. The tubing 19 is made of asuitable non-toxic material that is preferably more flexible than theproximal shaft 13. A presently preferred material for the tubing 19 isbraided polyurethane, i.e., polyurethane with an embedded mesh ofbraided stainless steel or the like. The outer diameter of the distalshaft 14, like that of the proximal shaft 13, is preferably no greaterthan about 8 French.

A preferred means for attaching the proximal shaft 13 to the distalshaft 14 is illustrated in FIG. 5. The proximal end of the distal shaft14 comprises an inner counter bore 24 that receives the outer surface ofthe stiffener 20. The distal shaft 14 and proximal shaft 13 are attachedby glue or the like. Other methods for attaching the proximal shaft 13to the distal shaft 14 can be used in accordance with the invention.

The stiffening tube 20 is held in place relative to the outer wall 22 atthe proximal shaft 13. In a preferred construction of the proximal shaft13, a force is applied to the proximal end of the stiffening tube 20,which causes the distal end of the stiffening tube 20 to firmly pushagainst the counter bore 24. While under compression, a first glue jointis made between the stiffening tube 20 and the outer wall 22 by a fastdrying glue, e.g. Super Glue®. Thereafter a second glue joint is formedbetween the proximal ends of the stiffening tube 20 and outer wall 22using a slower drying but stronger glue, e.g., polyurethane.

The depicted catheter includes a mechanism for deflecting the distalshaft 14 of the catheter body 12. In the depicted embodiment, a pullerwire 42 extends into the puller wire lumen 32 of the distal shaft 14.The puller wire 42 is anchored at its proximal end to the deflectioncontrol handle 16 and anchored at its distal end to the distal shaft 14.The puller wire 42 is made of any suitable metal, such as stainlesssteel or Nitinol, and is preferably coated with Teflon® or the like. Thecoating imparts lubricity to the puller wire 42. The puller wire 42preferably has a diameter ranging from about 0.006 to about 0.010inches.

Referring to FIG. 5, the compression coil 44 extends from the proximalend of the proximal shaft 13 to the proximal end of the distal shaft 14.The compression coil 44 is made of any suitable metal, preferablystainless steel. The compression coil 44 is tightly wound on itself toprovide flexibility, i.e., bending, but to resist compression. The innerdiameter of the compression coil 44 is preferably slightly larger thanthe diameter of the puller wire 42. For example, when the puller wire 42has a diameter of about 0.007 inches, the compression coil 44 preferablyhas an inner diameter of about 0.008 inches. The Teflon® coating on thepuller wire 42 allows it to slide freely within the compression coil 44.Along its length, the outer surface of the compression coil 44 iscovered by a flexible, non-conductive sheath 26 to prevent contactbetween the compression coil 44 and any of the lead wires 129 or needleelectrode assembly 46. A non-conductive sheath 26 made of polyimidetubing is presently preferred. As shown in FIG. 5, the compression coil44 is anchored at its proximal end to the proximal end of the stiffeningtube 20 in the proximal shaft 13 by glue to form a glue joint 50 and atits distal end to the distal shaft 14 in the puller wire lumen 32.

The puller wire 42 extends into the puller wire lumen 32 of the distalshaft 14. Preferably the puller wire 42 is anchored at its distal end tothe side of the distal shaft 14, as shown in FIGS. 10 to 12. In thisembodiment, a T-shaped anchor 93 is formed which comprises a short pieceof tubular stainless steel 94, e.g., hypodermic stock, which is fittedover the distal end of the puller wire 42 and crimped to fixedly secureit to the puller wire. The distal end of the tubular stainless steel 94is fixedly attached, e.g., by welding, to a stainless steel cross-piece96, such as stainless steel ribbon or the like. The cross-piece 96 sitsin a notch 98 in a wall of the distal shaft 14 that extends into thesecond lumen 32. The stainless steel cross-piece 96 is larger than thenotch 98 and, therefore, cannot be pulled through the notch. The portionof the notch 98 not filled by the cross-piece 96 is filled with glue orthe like, preferably a polyurethane glue, which is harder than thematerial of the distal shaft 14. Rough edges, if any, of the cross-piece96 are polished to provide a smooth, continuous surface with the outersurface of the distal shaft 14.

With further reference to FIG. 5, within the distal shaft 14, and distalto the glue joint 50, the turns of the compression coil are expandedlongitudinally. Such expanded turns 49 are both bendable andcompressible and preferably extend for a length of about 0.5 inch. Thepuller wire 42 extends through the expanded turns 49 then into aplastic, preferably Teflon®, sheath 81, which prevents the puller wirefrom cutting into the wall of the distal shaft 14 when the distal shaftis deflected.

Any other suitable technique for anchoring the puller wire 42 in thedistal shaft 14 can also be used. Alternatively, other means fordeflecting the distal region can be provided, such as the deflectionmechanism described in U.S. Pat. No. 5,537,686, the disclosure of whichis incorporated herein by reference.

Longitudinal movement of the puller wire 42 relative to the catheterbody 12, which results in deflection of the distal shaft 14, isaccomplished by suitable manipulation of the control handle 16. Examplesof suitable control handles for use in the present invention aredisclosed, for example, in U.S. Pat. Nos. Re 34,502, 5,897,529 and6,575,931, the entire disclosures of which are incorporated herein byreference.

If desired, the catheter can include two or more puller wires (notshown) to enhance the ability to manipulate the distal shaft 14. In suchan embodiment, a second puller wire and a surrounding second compressioncoil extend through the proximal shaft 13 and into separate off-axislumens (not shown) in the distal shaft. Suitable deflection controlhandles for use with a catheter having more than one puller wire aredescribed in U.S. Pat. Nos. 6,123,699, 6,171,277, and 6,183,463, thedisclosures of which are incorporated herein by reference.

As shown in FIG. 3, a needle electrode assembly 46 is provided. Theneedle electrode assembly 46 is used to ablate tissue whilesimultaneously injecting saline or other fluid to conduct the ablationenergy, thereby creating a theoretic increase in the effective size ofthe electrode. The needle electrode assembly 46 is extendable andretractable, and may be moved by manipulation of the needle controlhandle 17, as described further below. FIG. 3 depicts the needleelectrode assembly 46 in an extended position as it would be to ablatetissue. The distal end of the needle electrode assembly 46 may bewithdrawn into the infusion lumen 30 to avoid injury, particularlyduring the time that the catheter is inserted through the vasculature ofthe body and during the time in which the catheter is removed from thebody.

The needle electrode assembly 46 comprises a proximal tubing 33 joined,directly or indirectly, to a generally rigid, electrically-conductivedistal tubing 35, as shown in FIG. 3. The generally rigid nature of thedistal tubing 35 allows it to pierce tissue in order to increase itseffectiveness during ablation. In an exemplary embodiment, the distaltubing 35 is formed of Nitinol or stainless steel, and, as illustratedin FIG. 3, is preferably formed with a beveled edge 36 at the distal tipof the needle electrode assembly 46 to enhance its ability to piercetissue. The proximal tubing 33 is preferably more flexible than thedistal tubing 35 to allow the proximal tubing to bend as necessary withthe flexible proximal shaft 13 of the catheter body 12, for instancewhen the catheter is inserted into the vasculature of the body. Theproximal tubing 33 of the needle electrode assembly 46 is preferablymade of polyimide or polyether etherketone (PEEK), but can be made ofany other suitable biocompatible material, such as plastic or metal.

A needle electrode lead wire 210 is electrically connected at its distalend to the electrically-conductive distal tubing 35 for supplying radiofrequency energy or other suitable ablation energy to the distal tubing.The needle electrode lead wire 210 is soldered, welded or otherwiseattached to the outside of the distal tubing 35, but could be attachedelsewhere to the distal tubing. The proximal end of the needle electrodelead wire 210 is attached to a suitable connector 67, which in turn isconnected to a suitable source of ablation energy (not shown).

Additionally, a temperature sensor is provided for measuring thetemperature of the tissue being ablated by the needle electrode assembly46 before, during or after ablation. Any conventional temperaturesensor, e.g., a thermocouple or thermistor, may be used. In the depictedembodiment, the temperature sensor comprises a thermocouple 200 formedby an enameled wire pair, as best shown in FIG. 4. One wire of the wirepair is a copper wire 202, e.g., a number 40 copper wire. The other wireof the wire pair is a constantan wire 204. The wires 202 and 204 of thewire pair are electrically isolated from each other except at theirdistal ends, where they are twisted together, covered with a short pieceof plastic tubing 206, e.g., polyimide, and covered with epoxy. Theplastic tubing 206 is then glued or otherwise attached to the insidewall of the distal tubing 35 of the needle electrode assembly 46, asbest shown in FIG. 3. The proximal ends of the wires 202 and 204 extendout the proximal end of the distal tubing 35 and are attached to anappropriate connector (not shown) connectable to a suitable temperaturemonitor (not shown). In an alternative embodiment, the copper wire 202of the thermocouple can also be used as the lead wire for the needleelectrode assembly 46

The proximal tubing 33 of the needle electrode assembly 46 extends fromthe needle control handle 17, through the deflection control handle 16,through the proximal shaft 13, and into the infusion lumen 30 of thedistal shaft 14. The proximal end of the distal tubing 35 is spacedslightly from the distal end of the proximal tubing 33 and extendsthrough the infusion lumen 30 of the distal shaft 14. The proximal anddistal tubings 33 and 35 are mounted, preferably coaxially, within anouter plastic tube 48. The outer plastic tube 48 can be glued orotherwise attached to the proximal and distal tubings to form a singlestructure that, as described below, is longitudinally moveable relativeto the catheter body 12. The outer plastic tube 48 extends through thecatheter body 12 with the proximal tubing and protects the needleelectrode lead wire 210 and thermocouple wires 202 and 204, which extendbetween the proximal tubing 33 and outer plastic tube 48, when theneedle electrode assembly 46 is moved relative to the catheter body. Theneedle electrode lead wire 210 and thermocouple wires 202 and 204 extendout through a hole (not shown) in the outer plastic tube 48 within thedeflection control handle 16 and are attached to appropriate connectors,as noted above.

FIG. 3 shows one arrangement for joining the outer plastic tube 48 tothe proximal and distal tubings 33 and 35. Specifically, a small pieceof plastic tubing 45, for example, polyimide tubing, is placed over thediscontinuity between the proximal and distal tubings 33 and 35 andattached to the proximal and distal tubings by polyurethane glue or thelike to form a single infusion passage through which saline or otherfluid can pass from the proximal tubing to the distal tubing. The smallpiece of plastic tubing 45 helps to protect the thermocouple wires 202and 204 and the needle electrode lead wire 210. A small, preferablynon-conductive, spacer 43 is mounted between the distal tubing 35 andthe distal end of the outer plastic tube 48, and optionally glued inplace. The spacer 43 prevents bodily fluid from entering into the distalend of the needle electrode assembly 46,

In an exemplary embodiment, the proximal tubing 33 of the needleelectrode assembly 46 has an inner diameter of 0.014 inch and an outerdiameter of 0.016 inch. The distal tubing 35 has an inner diameter of0.014 inch and an outer diameter of 0.018 inch and a length of about 1.0inch. Further, the distal tubing 35 extends past the distal end of thedistal shaft 14 about 14 mm. The small plastic tubing 45 has an innerdiameter of 0.022 inch and an outer diameter of 0.024, the outer plastictube 48 has an inner diameter of 0.025 inch and an outer diameter of0.035 inch, and the plastic spacer 43 has an inner diameter of 0.017inch and an outer diameter of 0.024 inch.

Within the catheter body 12, the needle electrode assembly 46,comprising the proximal tubing 33, distal tubing 35, spacer 43, plastictubing 45 and outer plastic tube 48, is slidably mounted, preferablycoaxially, within a protective tube 47 that is stationary relative tothe catheter body. The protective tube 47, which is preferably made ofpolyimide, serves to prevent the needle electrode assembly 46 frombuckling during extension and retraction of the needle electrodeassembly relative to the catheter body 12. The protective tube 47additionally serves to provide a fluid-tight seal surrounding the needleelectrode assembly 46. Within the deflection control handle 16, theprotective tube 47 and needle electrode assembly 46 extend into aprotective shaft 66, which is preferably made of polyurethane.

Other needle electrode assembly designs are contemplated within thescope of the invention. For example, the needle electrode assembly cancomprise a single electrically-conductive tube, such as a Nitinol tube,that extends from the needle control handle 17 to the distal end of thecatheter. Such a design is described in U.S. patent application Ser. No.09/711,648, entitled “Injection Catheter with Needle Electrode,” thedisclosure of which is incorporated herein by reference.

Longitudinal movement of the needle electrode assembly 46 is achievedusing the needle control handle 17. The needle electrode assembly 46 andprotective tube 47 extend from the deflection control handle 16 to theneedle control handle 17 within the protective shaft 66.

As illustrated in FIG. 2, in one embodiment the needle control handle 17comprises a generally cylindrical outer body 80 having proximal anddistal ends, a piston chamber 82 extending a part of the waytherethrough, and a needle passage 83 extending a part of the waytherethrough. The piston chamber 82 extends from the proximal end of thehandle part way into the body 80, but does not extend out the distal endof the body. The needle passage 83, which has a diameter less than thatof the piston chamber 82, extends from the distal end of the pistonchamber to the distal end of the outer body 80.

A piston 84, having proximal and distal ends, is slidably mounted withinthe piston chamber 82. A proximal fitting 86 is mounted in and fixedlyattached to the proximal end of the piston 84. The proximal fitting 86includes a tubular distal region 87 that extends distally from the mainbody of the proximal fitting. The piston 84 has an axial passage 85through which the proximal tubing 33 of the needle electrode assembly 46extends, as described in more detail below. A compression spring 88 ismounted within the piston chamber 82 between the distal end of thepiston 84 and the outer body 80. The compression spring 88 can either bearranged between the piston 84 and outer body 80, or can have one end incontact with or fixed to the piston, while the other end is in contactwith or fixed to the outer body.

The proximal tubing 33, outer plastic tube 48, protective tube 47 andprotective shaft 66 extend from the deflection control handle 16 intothe distal end of the needle passage 83, as best shown in AREA A of FIG.2. Within the needle passage 83, the proximal tubing 33, outer plastictube 48, protective tube 47 and protective shaft 66 extend into a firstmetal tube 90, which is preferably made of stainless steel. If desired,the first metal tube 90 could instead be made of a rigid plasticmaterial. The first metal tube 90 is secured to the outer body 80 of theneedle control handle 17 by a set screw 101 or any other suitable means.The protective shaft 66 terminates at its proximal end within the firstmetal tube 90.

A second metal tube 91 is provided with its distal end mounted,preferably coaxially, inside the proximal end of the first metal tube 90and with its distal end abutting the proximal end of the protectiveshaft 66. The second metal tube 91 is fixed in place relative to thefirst metal tube 90 by the set screw 101. The second metal tube 91, likethe first metal tube 90, could alternatively be made of a rigid plasticmaterial.

The proximal end of the second metal tube 91 is mounted, preferablycoaxially, around the distal end of the tubular distal region 87 of theproximal fitting 86, with the second metal tube being longitudinallymovable relative to the tubular distal region 87. Accordingly, when thepiston 84 is moved distally relative to the outer body 80, the tubulardistal region 87 moves distally into the second metal tube 91. As shownin AREA B of FIG. 2, the proximal tubing 33 and outer plastic tube 48extend through the second metal tube 91 and into the tubular distalregion 87 of the proximal fitting 86. The outer plastic tube 48terminates in and is fixedly attached to the proximal fitting 86 tothereby attach the outer plastic tube, and thus the needle electrodeassembly 46, to the piston 84. Within the proximal fitting 86, theproximal tubing 33 extends out of the outer plastic tube 48 and into afirst protective sheath 31, as shown in AREA C of FIG. 2, and isconnected to a luer connector 65, which is connected to an irrigationpump or other suitable fluid infusion source (not shown), as is known inthe art. Similarly, the needle electrode lead wire 210 and thethermocouple wires 202 and 204 extend out of the outer plastic tube 48and into a second protective sheath 29, as also shown in AREA C of FIG.2, which is connected to a suitable connector 67, such as a 10-pinelectrical connector, for connecting the needle electrode lead wire to asource of ablation energy and the thermocouple wires to a suitablemonitoring system.

In use, force is applied to the piston 84 to cause distal movement ofthe piston relative to the outer body 80, which compresses thecompression spring 88. This movement causes the needle electrodeassembly 46 to correspondingly move distally relative to the outer body80, protective shaft 66, protective tube 47, proximal shaft 13, anddistal shaft 14 so that the distal tubing 35 of the needle electrodeassembly extends outside the distal end of the distal shaft. When theforce is removed from the piston 84, the compression spring 88 pushesthe piston proximally to its original position, thus causing the distaltubing 35 of the needle electrode assembly 46 to retract back into thedistal end of the distal shaft 14. Upon distal movement of the piston84, the tubular distal region 87 of the proximal fitting 86 movesdistally into the second metal tube 91 to prevent the proximal tubing 33and the outer plastic tube 48 of the needle electrode assembly 46 frombuckling within the axial passage 85.

The piston 84 further comprises a longitudinal slot 100 extending alonga portion of its outer edge. A securing means 102, such as a set screw,pin, or other locking mechanism, extends through the outer body 80 andinto the longitudinal slot 100. This design limits the distance that thepiston 84 can be slid proximally out of the piston chamber 82. When theneedle electrode assembly 46 is in the retracted position, preferablythe securing means 102 is at or near the distal end of the longitudinalslot 100.

The proximal end of the piston 84 has a threaded outer surface 104. Acircular thumb control 106 is rotatably mounted on the proximal end ofthe piston 84. The thumb control 106 has a threaded inner surface 108that interacts with the threaded outer surface 104 of the piston. Thethumb control 106 acts as a stop, limiting the distance that the piston84 can be pushed into the piston chamber 82, and thus the distance thatthe needle electrode assembly 46 can be extended out of the distal endof the catheter. The threaded surfaces of the thumb control 106 andpiston 84 allow the thumb control to be moved closer or farther from theproximal end of the outer body 80 so that the extension distance of theneedle electrode assembly 46 can be controlled by the physician. Asecuring means, such as a tension screw 110 is provided in the thumbcontrol 106 to control the tension between the thumb control and piston84. As would be recognized by one skilled in the art, the thumb control106 can be replaced by any other mechanism that can act as a stop forlimiting the distance that the piston 84 extends into the piston chamber82, and it is not necessary, although it is preferred, that the stop beadjustable relative to the piston.

As noted above, the mapping assembly 15 is mounted on the distal end ofthe distal shaft 14. With reference to FIGS. 3 and 8, the mappingassembly 15 comprises two or more flexible spines 118. Each spine 118has a proximal end attached to the distal end of the catheter body 12and a free distal end, i.e., the distal end is not attached to any ofthe other spines, to the catheter body, or to any other structure thatconfines movement of the distal end of that spine. As will be recognizedby one skilled in the art, the number of spines 118 can vary as desireddepending on the particular application, so that the mapping assembly 15has at least two spines, preferably at least three spines, morepreferably at least five spines and as many as eight or more spines. Thespines 118 are moveable between an expanded arrangement, wherein, forexample, each spine arcs outward from the distal end of the catheterbody 12, as shown in FIG. 8, and a collapsed arrangement (not shown),wherein, for example, each spine is disposed generally along alongitudinal axis of the catheter body so that the spines are capable offitting within a lumen of a guiding sheath. As described in more detailbelow, each spine 118 carries at least one electrode, preferably a ringelectrode, such that when the spines are positioned in contact withheart tissue, each spine is capable of obtaining electrical andmechanical data.

In the embodiment shown in FIG. 8, the mapping assembly 15 includes fivespines 118, and each spine has a pre-formed configuration in which thespine arcs outwardly from the catheter body 12. However, other spineshapes and configurations are contemplated within the invention. Withreference to FIG. 3, each spine 118 comprises a support arm 124 and anon-conductive covering 134 in surrounding relation to the support arm124. The support arm 124 comprises a metal or plastic material that hasshape memory, such that the support arm forms an initial shape (i.e.,part of the expanded configuration) when no external forces are applied,forms a deflected shape (e.g., part of the collapsed configuration) whenexternal force is applied, and returns to its initial shape when theexternal force is released. In one embodiment, each support arm 124comprises a superelastic material, for example, a nickel-titanium alloysuch as nitinol. In a preferred embodiment, the non-conductive covering134 comprises a biocompatible plastic tubing, such as polyurethane orpolyimide tubing. The non-conductive covering 134 may be glued to thesupport arm 132 or attached indirectly by being glued to the distal endof the distal tubing 35. The non-conductive covering 134 may be attachedto the support arm 124 by any other suitable method.

As noted above, each spine 118 carries at least one electrode mountedalong its length. In the depicted embodiment, four ring electrodes 125are mounted on the non-conductive covering 134 of each spine 118, butfewer or additional ring electrodes may be used as desired. Each ringelectrode 125 has a length preferably up to about 2 mm, more preferablyfrom about 0.5 mm to about 1 mm. Preferably the ring electrodes 125 aregenerally evenly-spaced along the length of each spine 118.

Each ring electrode 125 is electrically connected to an electrode leadwire 129, which in turn is electrically connected to a connector (notshown), which can be incorporated into the deflection control handle 16or provided outside of the catheter. The connector is connected to anappropriate mapping or monitoring system (not shown). Each electrodelead wire 129 extends from the connector, through the deflection controlhandle 16, through the central lumen 18 in the proximal shaft 13 of thecatheter body 12, through the lead wire lumen 34 of the distal shaft 14,and into the non-conductive covering 134 of one of the spines 118, whereit is attached to its corresponding ring electrode 125. Within theproximal shaft 13 and deflection control handle 16, the lead wires 129extend through a protective tube 70, which can be eliminated if desired.

Each lead wire 129, which includes a non-conductive coating over almostall of its length, is attached to its corresponding ring electrode 125by any suitable method. An exemplary method for attaching a lead wire129 to a ring electrode 125 involves first making a small hole throughan outer wall of the non-conductive covering 134. Such a hole can becreated, for example, by inserting a needle through the non-conductivecovering 134 and heating the needle sufficiently to form a permanenthole. The lead wire 129 is then drawn through the hole by using amicrohook or the like. The end of the lead wire 129 is then stripped ofany coating and welded to the underside of the ring electrode 125, whichis then slid into position over the hole and fixed in place withpolyurethane glue or the like. Alternatively, each ring electrode 125may be formed by wrapping the lead wire 129 around the non-conductivecovering 134 a number of times and stripping the lead wire of its ownnon-conductive coating on its outwardly facing surfaces. In such aninstance, the lead wire 129 functions as a ring electrode.

In the depicted embodiment, two of the spines 118 each carry a markerband 130 to help the user identify the orientation of the mappingassembly 15 under fluoroscopy. Each marker band 130 comprises a metalring (e.g., a ring electrode not attached to a lead wire) of sufficientradiopacity. The marker bands 130 may be placed along any part of thespine 118, as long as they are not in contact with any of the ringelectrodes 125. Preferably, a first marker band 130 a is placed on afirst spine 118 a between the most proximal ring electrode 125 a and thedistal shaft 14, and a second marker band 130 b is placed on a secondspine 118 b between the most proximal ring electrode 125 a and thesecond most proximal ring electrode 125 b.

In the depicted embodiment, the spines 118 of the mapping assembly 15are supported and given their desired shape by a support structure 120comprising a base 122 and plurality of support arms 124 extending fromthe base, as best shown in FIG. 9. The base 122 of the support structure120 is generally cylindrically shaped for mounting over the distal endof the tubing 19 of the distal shaft 14. The support arms 124 each havea proximal end attached to the base 122 and a free distal end, asdescribed above. The number of support arms 124 on the support structurecorresponds to the desired number of spines 118 on the mapping assembly,and in the depicted embodiment is five.

In a preferred embodiment, the support structure 120 is manufacturedfrom a single metal tube, and thus has a unitary structure. In aparticularly preferred embodiment, the support structure 120 ismanufactured from a nickel-titanium alloy, for instance, Nitinol.Preferably, the base is a right circular cylinder and has a diameterslightly larger than the distal end of the distal shaft 14.

In the depicted embodiment, each support arm 124 is tapered slightlyfrom its proximal end to its distal end, which allows for greater distalflexibility while maintaining the desired curvature at the proximal end.Each support arm 124 also includes a disc-shaped tip 127, which providesmore surface area for the distal end of the support arm 124 to be gluedto its corresponding non-conductive covering 134.

During assembly, the base 122 of the support structure 120 is mountedover the distal end of the tubing 19 of the distal shaft 14.Non-conductive coverings 134 are introduced over the support arms 124 toform the spines 118 of the mapping assembly 15. After the ringelectrodes 125 are mounted on the spines 118 as described above and theother desired components are assembled within the catheter, a piece oftubular plastic 208 is mounted over the base 122 of the supportstructure 120 and optionally glued in place. The piece of tubularplastic 208 also covers the proximal ends of the non-conductivecoverings 134.

Other methods and structures for forming and supporting the mappingassembly are within the scope of the invention. An example of analternative design for the mapping assembly according to the inventionis described in U.S. patent application Ser. No. 10/040,932, entitled“Catheter Having Multiple Spines Each Having Electrical, Mapping andLocation Sensing Capabilities,” the disclosure of which is incorporatedherein by reference.

In the depicted embodiment, as shown in FIG. 3, the catheter furtherincludes at least one location sensor 140. The location sensor 140 isused to determine the coordinates of the mapping assembly 15 at eachinstant when the mapping assembly 15 is being used to collect one ormore electrical mapping data points. As a result, both electrical andlocational data can be obtained for each data point that is mapped. Inthe depicted embodiment, a single location sensor 140 is mounted in thedistal end of the distal shaft 14 within the cylindrical base 122 of thesupport structure 120. Alternatively, the catheter can include multiplelocation sensors 140, one mounted within each spine 118 of the mappingassembly 15, as described in U.S. patent application Ser. No.10/040,932, entitled “Catheter Having Multiple Spines Each HavingElectrical, Mapping and Location Sensing Capabilities,” the entiredisclosure of which is incorporated herein by reference.

The location sensor 140 is connected to a corresponding sensor cable 74.The sensor cable 74 extends, along with the lead wires 129, through thelead wire lumen 34 of the distal shaft 14, and through the proximalshaft 13 within the protective tube 70 and then into the deflectioncontrol handle 16 and out of the proximal end of the deflection controlhandle within an umbilical cord (not shown) to a sensor control module(not shown) that houses a circuit board (not shown). Alternatively, thecircuit board can be housed within the control handle 16, for example,as described in U.S. Pat. No. 6,024,739, the disclosure of which isincorporated herein by reference. The sensor cable 74 comprises multiplewires encased within a plastic covered sheath. In the sensor controlmodule, the wires of the sensor cable 74 are connected to the circuitboard. The circuit board amplifies the signal received from the locationsensor 140 and transmits it to a computer in a form understandable bythe computer by means of a sensor connector at the proximal end of thesensor control module. Also, because the catheter is designed for singleuse only, the circuit board preferably contains an EPROM chip that shutsdown the circuit board approximately twenty-four hours after thecatheter has been used. This prevents the catheter, or at least thelocation sensor 140, from being used twice.

Preferably the location sensor 140 is an electromagnetic locationsensor. For example, the location sensor 140 may comprise amagnetic-field-responsive coil, as described in U.S. Pat. No. 5,391,199,or a plurality of such coils, as described in International PublicationWO 96/05758. The plurality of coils enables the six-dimensionalcoordinates (i.e. the three positional and the three orientationalcoordinates) of the location sensor 140 to be determined. Alternatively,any suitable location sensor known in the art may be used, such aselectrical, magnetic or acoustic sensors. Suitable location sensors foruse with the present invention are also described, for example, in U.S.Pat. Nos. 5,558,091, 5,443,489, 5,480,422, 5,546,951, and 5,568,809,International Publication Nos. WO 95/02995, WO 97/24983, and WO98/29033, and U.S. patent application Ser. No. 09/882,125 filed Jun. 15,2001, entitled “Position Sensor Having Core with High PermeabilityMaterial,” the disclosures of which are incorporated herein byreference.

Using this technology, the physician can visually map a heart chamber.This mapping is done by advancing the distal shaft 14 into a heartchamber until contact is made with the heart wall. This position isrecorded and saved. The distal shaft 14 is then moved to anotherposition in contact with the heart wall and again the position isrecorded and saved.

The location sensor 140 can be used alone or more preferably incombination with the ring electrodes 125. By combining the locationsensor 140 and electrodes 125, a physician can simultaneously map thecontours or shape of the heart chamber, the electrical activity of theheart, and the extent of displacement of the catheter and hence identifythe presence and location of the ischemic tissue. Specifically, thelocation sensor 125 is used to monitor the precise location of thedistal end of the catheter in the heart and the extent of catheterdisplacement. The ring electrodes 125 are used to monitor the strengthof the electrical signals at that location.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningful departing from the principal, spirit and scope ofthis invention.

Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest and fairscope.

1. An injection catheter comprising: an elongated catheter body havingat least one lumen extending longitudinally therethrough; a needlecontrol handle at the proximal end of the catheter body; a needleelectrode assembly extending through the catheter body and needlecontrol handle and having a proximal end attached to the needle controlhandle and a distal end within the distal end of the catheter body; anda mapping assembly, having proximal and distal ends, mounted at thedistal end of the catheter body and comprising at least two flexiblespines, each spine having a proximal end attached at the distal end ofthe catheter body and a free distal end, wherein each spine carries atleast one electrode; wherein the distal end of the needle electrodeassembly is extendable past the proximal end of the mapping assemblyupon manipulation of the needle control handle.
 2. The catheter of claim1, wherein each spine comprises a non-conductive covering having asupport arm that has shape memory disposed therein.
 3. The catheter ofclaim 2, wherein each support arm comprises Nitinol.
 4. The catheter ofclaim 1, wherein the mapping assembly is moveable between an expandedarrangement, in which each spine extends radially outward from thecatheter body, and a collapsed arrangement, in which each spine isdisposed generally along a longitudinal axis of the catheter body. 5.The catheter of claim 4, wherein, when the mapping assembly is in itsexpanded arrangement, each spine extends radially outwardly from thecatheter body and forms an arced shape.
 6. The catheter of claim 1,wherein the mapping assembly comprises at least five spines.
 7. Thecatheter of claim 1, further comprising an electrode lead wire having afirst end electrically connected to the needle electrode assembly and asecond end electrically connected to a source of ablation energy.
 8. Thecatheter of claim 1, wherein the needle electrode assembly comprises adistal tubing having proximal and distal ends and comprising anelectrically conductive material and a proximal tubing comprising amaterial more flexible than the distal tubing and having a distal endattached, directly or indirectly, to the proximal end of the distaltubing.
 9. The catheter of claim 8, wherein the distal tubing comprisesmetal and the proximal tubing comprises plastic.
 10. The catheter ofclaim 8, wherein the distal tubing comprises Nitinol or stainless steel.11. The catheter of claim 8, wherein the proximal tubing comprisespolyimide or PEEK.
 12. The catheter of claim 8, wherein the distal endof the distal tubing forms a beveled edge.
 13. The catheter of claim 8,wherein the needle electrode assembly further comprises an intermediatetubing joining the proximal and distal tubings.
 14. The catheter ofclaim 8, wherein the needle electrode assembly further comprises anouter plastic tubing fixedly attached, directly or indirectly, to theproximal and distal tubings so that the outer plastic tubing is moveablewith the proximal and distal tubings relative to the catheter body. 15.The catheter of claim 14, wherein the electrode lead wire is fixedlyattached to the distal tubing and extends within the outer plastictubing and outside the proximal tubing.
 16. The catheter of claim 8,further comprising a temperature sensor mounted within the distaltubing.
 17. The catheter of claim 1, further comprising a temperaturesensor mounted in or around the needle electrode assembly.